If you need it at the database end then you can use a sequence. If you want at the application end then use java UUID generator.

If you are talking about a pega data table like pr_other, the table has pzinskey as the primary key and the value is generated by pega using the defined keys on your class. If you are talking about a non pega table, you can use sequence or java features as stated in this link(http://www.javapractices.com/topic/TopicAction.do?Id=56).

Thanks,

Ashok